Implantable Medical Device for Improved Placement and Adherence in the Body

ABSTRACT

A medical device comprises a flexible member that can be adhesively attached to a housing of the medical device, allowing implantation of the medical device into a body through an incision of reduced size. The flexible member can be attached to the housing either before or after implantation into the body. The flexible member comprises suture locations, including a permeable membrane or a suture hole, for suturing the medical device to tissue of the body. The suture holes can be filled with a substance penetrable by a suture needle, to minimize tissue ingrowth before or after suturing.

FIELD OF THE INVENTION

This invention relates generally to implanted medical devices used toaccess subcutaneous regions within a body, such as vasculature.

BACKGROUND OF THE INVENTION

Long term access to a patient's body is required for many medicaltreatments including antibiotic therapy, hemodialysis access,chemotherapy regimens, and other treatments that require repeatedadministration, withdrawal, or exchange of fluids. In some cases,internal access to the patient is required for years.

Subcutaneously implanted access ports are one type of medical devicethat can be used for this purpose. These medical devices often eitherinclude or are attached to a catheter used for the administration,withdrawal, and/or exchange of fluids from the patient. A pocket is madein the subcutaneous tissue, and the medical device is placed into thepocket.

Access ports generally have a molded or rigid housing, with a fixednumber of suture holes. These suture holes protrude from the housing ofthe medical device, causing it to have a larger overall size than itotherwise would have. During implantation, a physician is thus requiredto create an incision in the body of sufficient size to allow insertionof the device. Further, rigid appendages on the housing of the medicaldevice can make manipulation of the device within the body of a patientdifficult for a physician.

Suturing of such a device can be performed by the physician to secure orstabilize the device. A number of factors determine whether or not themedical device is sutured in place, including the pocket configuration,the type of training received by the physician, and the physician'spreference. Once the device is properly positioned and secured, thepocket is closed.

There is a wide range of preferences among physicians regarding thenumber and location of suture holes. Some physicians prefer one, two,three, four, or more suture holes. Some physicians prefer not to haveany suture holes, and yet others prefer to have any suture holes thatare present filled with a material such as silicone to minimize fibriningrowth into the suture holes, thereby facilitating subsequent removalof the device.

After suturing has been completed, the rigid housing of the medicaldevice and the associated suture holes do not readily accommodatemovement of the patient. Movement of the patient causes the tissue towhich the medical device has been sutured to move. The rigidity of thedevice thus results in increased tension on the sutures, resulting indiscomfort and irritation to the patient.

SUMMARY OF THE INVENTION

In one aspect, the invention features an implantable medical device forpercutaneous access to a body comprising a flexible member and a housingdefining an entry site for the administration, withdrawal, or exchangeof fluids. The flexible member is attached to a surface of the housingand stabilizes placement of the medical device within the body. Anadhesive is disposed on a first surface of the flexible member andattaches the flexible member to the housing surface. The flexible membercan comprise suture locations, and the suture locations can define oneor more suture holes. The suture holes can be filled with a material tominimize tissue ingrowth, such as fibrin. The material can be siliconeor a biocompatible polymer, and is preferably penetrable by a sutureneedle.

The flexible member can have a perimeter region penetrable by a sutureneedle, which can be formed of materials including polyurethane,thermoplastics, elastomers, and fiber reinforced elastomers. Theflexible member can also include tabs, which can be located about aperimeter of the flexible member. The tabs can define one or more sutureholes.

The flexible member can be coated with a tissue growth substance and canbe shaped and/or textured to conform to tissue within the body. A secondsurface of the flexible member can include an adhesive for attaching thedevice to tissue within the body. The flexible member can be preformedto mate with the housing. It can also be shaped to surround a perimeterof the housing.

Another aspect of the invention features a flexible member forstabilizing the placement of a medical device within a body. Theflexible member includes a flexible substrate that mates with themedical device, one or more suture locations formed on the flexiblesubstrate, and an adhesive. The flexible member can be formed from amaterial penetrable by a suture needle. Materials such as polyurethanes,thermoplastics, elastomers, and fiber-reinforced elastomers can be usedto form the flexible member.

The flexible member can comprise one or more suture locations, and thesecan each define one or more suture holes. The suture holes can be filledwith a tissue growth substance that inhibits tissue growth. The sutureholes can be filled with substances such as silicone and biocompatiblepolymers. In one embodiment, the substance is penetrable by a sutureneedle.

The flexible member can also include tabs, and the labs can be disposedabout the perimeter of the flexible member. The tabs can be flexible andcan be penetrable by a suture needle. The flexible member can be coatedwith a substance to inhibit tissue growth. It can also be preformed tomate with the perimeter of a surface of the medical device and can havea second surface shaped to conform to subcutaneous tissue within thebody.

At least a portion of the perimeter of the flexible member can follow aperimeter of the surface of the medical device to which the flexiblemember is attached. The flexible member can include an adhesive tosecure the flexible member to the medical device. The adhesive caninclude methoxy-perfluoropropane, thixotropic sealants, and water-basedadhesives.

Another aspect of the invention features a method of manufacturing animplantable medical device that comprises providing a housing definingan entry site for the administration, withdrawal, or exchange of fluids,and attaching a flexible member thereto, for stabilizing placement ofthe housing within the body. The flexible member can be formed bycutting a sheet of polymer. The method can include applying an adhesiveto the flexible member by at least one of spray coating, slot coating,spiral spraying, melt-blowing, pattern coating, layering, dipping anddrying, and ion deposition.

Another aspect of the invention features a method of fabricating aflexible member which includes forming a shape for mating with animplantable medical device, forming suture locations about the shape ofthe flexible member, and applying an adhesive to the shape. The shapecan be formed by cutting from a sheet of polymer, and suture holes canbe formed in the flexible member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention are more fully described belowin the detailed description and accompanying drawings of which thefigures illustrate an apparatus and method for securing an implantablemedical device within a body.

FIG. 1 illustrates a prior art device used to provide access to provideaccess to subcutaneous regions within a body, such as vasculature.

FIG. 2 illustrates another prior art device with only one entry site.

FIG. 3 illustrates a side elevation view of an embodiment of theinvention.

FIG. 4 illustrates a side and top view of another embodiment of theinvention.

FIGS. 5-8 are a top view of other embodiments of the invention.

FIGS. 9 and 10 are perspective views that show different ways theflexible member can be attached to a surface of a medical device.

FIGS. 11-14 are top views illustrating additional embodiments of theinvention.

FIG. 15 is a side view of a flexible member shaped to conform to tissuewithin the body.

FIG. 16 is a side view of a flexible member that is preformed to matewith a medical device.

FIGS. 17-18 illustrate embodiments of the invention with differentthickness characteristics.

FIGS. 19 and 20 each illustrate an embodiment of the invention withdifferent surface textures.

FIG. 21 is a flow chart illustrating steps that can be used tomanufacture a flexible member of the invention.

FIG. 22 is a flow chart illustrating steps that can be used by aphysician to prepare the flexible member for use.

FIG. 23 is a flow chart illustrating steps that can be used to implant amedical device of the invention.

DETAILED DESCRIPTION

FIG. 1 shows a prior art access port used by a physician to provideaccess to subcutaneous regions within the body, such as vasculature. Themedical device 10 includes a housing 11 and an entry site 12 for theadministration, withdrawal, or exchange of fluids. The entry site can bea septum. The needle of a syringe, for example, can be used toadminister or withdraw fluids through the septum. The medical device canbe surgically implanted beneath the skin of a patient.

The medical device can also include a predetermined number of sutureholes 14 disposed about the base of the housing in fixed locations. Thesuture holes can be molded into the housing 11 as shown. A physician cantie a suture through the suture hole, thus securing the medical device10, for example, to adjacent tissue. The medical device shown has twoentry sites 12.

FIG. 2 illustrates another prior art access port with a single entrysite 12. A catheter 22 is attached to the medical device 10. Sutureholes 14 are disposed about the base of the housing 11 at fixedlocations.

FIG. 3 is an illustration of an embodiment of an access portincorporating principles of the invention. The medical device 10comprises housing 11 and an entry site 12. The shape of the housing 11defines the entry site 12, as shown. The entry site is used toadminister, withdraw, or exchange fluids with a body, and can comprise aseptum. A physician can penetrate the septum with the needle of asyringe.

A flexible member 30 is attached to a surface 32 of the housing. Aperimeter region 35 of the member 30 is non-rigid and flexible. Whenflexed, the size of the incision required for insertion of the medicaldevice in a body can be reduced. Suture locations 38 are disposed alongthe perimeter region 35 of the flexible member 30.

FIG. 4 illustrates a flexible member 30 having a first surface 41 and asecond surface 44. The first surface 41 comprises an adhesive, whichallows the flexible member to be attached to the surface of the housing32. In one embodiment, the flexible member is preformed tape, having anadhesive surface that easily adheres to the surface of the housing 32.The tape can take various shapes, forms, thicknesses, and orientations.The flexible member 30 can be attached to the housing surface 32 beforesurgery. Adhesively attaching the flexible member 30 to housing surface32 of medical device 10 allows a physician to implant the medical devicewithin a body using an incision of reduced size. Alternatively, theflexible member can be attached to the housing surface afterimplantation into a body. This is accomplished by attaching the flexiblemember 30 to the housing 32 after each has been inserted into the bodythrough the incision. In this embodiment, the incision size can bereduced still further.

The flexibility of the member 30 also enhances the manipulation andplacement attributes of the device, providing a physician with increasedcapabilities and reducing aggravation and irritation to a patient.Patient recovery and comfort are thus enhanced. The flexible member alsoresults in improved comfort and reduced irritation to the patient afterthe medical device has been implanted. Movement of a patient causes thetissue to which the medical device has been sutured to move. Theresiliency of the flexible member thus reduces the stress to the bodytissues of the patient during movement of the patient. This results inreduced irritation to the body and increased patient comfort. If suturesare present (discussed below), the benefit of this feature is increased.

The perimeter region 35 of the flexible member 30 can extend beyond theperimeter 47 of the housing surface. As shown, the perimeter region 35of the flexible member 30 can extend beyond the perimeter of the housingsurface 47 on all sides. In other embodiments, the perimeter region 35can extend beyond the perimeter 47 of the housing surface on fewer thanall sides.

FIGS. 5-8 show a top view of different embodiments of the invention.FIGS. 5 and 6 illustrate a flexible member comprising a perimeter region35. This perimeter region 35 can extend beyond the perimeter of thehousing surface 47 when the flexible member is attached to surface 32 ofhousing 11. The perimeter region 35 can extend beyond the housingperimeter 47 in all directions, as shown. In other embodiments, itextends beyond the housing perimeter 47 in fewer directions. In any ofthese embodiments, a plurality of suture locations 38 can be disposedabout the perimeter region 35 of the flexible member 30.

FIGS. 7 and 8 illustrate flexible members 30 comprising preformed tabs72 that extend beyond the perimeter of the housing surface 47. Each ofthese tabs 72 can include one or more suture locations 38.

Each of the embodiments found in FIGS. 5-8 can be formed as a preformedflexible member. The shapes illustrated in these figures are intended toconform generally to the perimeter of the housing surface 47 to whichthey can be attached. In other embodiments, however, the flexible membermay not conform to the perimeter of the housing.

FIG. 9 illustrates the manner in which an embodiment of the flexiblemember 91 can be joined with the housing surface 32A of medical device10. Tabs 72 comprising suture locations 38 extend beyond the perimeterof the housing surface 47A providing locations to which a suture can beconveniently attached.

FIG. 10 illustrates a perspective view of another embodiment of aflexible member 101 that can be joined with the housing surface 32A ofmedical device 10. In this embodiment, the perimeter region 35 comprisessuture locations 38 and extends beyond the perimeter of the housingsurface 47A. As shown in FIGS. 9 and 10, both embodiments of theflexible member (91, 101) can be effectively attached to housing surface32A and efficiently mate with the perimeter 47A of the housing surface.When attached to the housing surface 32A, both embodiments (91 and 101)of the flexible member adhere to the entire housing surface 32A. Inother embodiments, this may not be required. Rather, the flexible membercan be shaped to adhere to only a portion of the housing surface. Thisis useful if it is necessary to stabilize only a portion of the medicaldevice.

FIG. 11 illustrates an asymmetrical embodiment of the invention. Inparticular, the perimeter region 35 extends further in the directionlabeled as “A” than in the other directions. Thus, the dimension of theperimeter region 35 of the flexible member 30 is larger in direction Athan in the other directions shown. This embodiment includes a pluralityof suture locations disposed in the perimeter region 35. The presence,location, and number of suture locations are determined by the needs andpreferences of the physician using the device.

FIG. 12 illustrates an embodiment of the flexible member 30 comprisingsuture locations 38 disposed both in a perimeter region 35 and on tabs72. It is not necessary for all or any of the suture locations 38 to besutured by a physician. This embodiment also illustrates that more thanone suture location 38 can be present on a tab 72.

FIG. 13 illustrates an embodiment of the flexible member 30 comprising ahole 131 in the center of the flexible member. Further, the suturelocations 38 are asymmetrically disposed about the perimeter region 35of the flexible member 30. This and other embodiments of a flexiblemember can be used to fulfill customized surgical requirements.

FIG. 14 illustrates a bottom view of an embodiment in which the flexiblemember 30 extends beyond the perimeter of the housing surface 47 at twoareas, labeled as X′ and X″ on the figure. Suture locations 38 arepresent at perimeter regions 35′ and 35″. As shown, portions of thehousing surface 32 are not in contact with the flexible member 30. Aphysician can also use this embodiment to meet varying surgicalrequirements and preferences. For example, in this embodiment exposedhousing surfaces 142 and 143 are not in contact with flexible member 30.Thus, a physician can grasp these surfaces directly and use them tomanipulate the medical device during implantation of the medical deviceinto a body. The desirability and utilization of this and other specificembodiments of the invention varies widely among physicians.

FIGS. 15-18 illustrate various thickness characteristics of the flexiblemember 30 of the invention. Each of these embodiments can include tabs72 and perimeter regions 35. In FIG. 15, the thickness of the flexiblemember 30 varies along its length. The medical device 10 is illustratedas being surgically positioned between a cutaneous layer 151 and atissue layer 154. The flexible member 30 includes a region of increasedthickness 156 and a region of lower thickness 157. The varying thicknessof the flexible member allows it to fit snugly between the surface ofthe housing 32 and the tissue layer 154. As shown, the contour of thesecond surface 44 of the flexible member is shaped to conform to theshape of the tissue layer 154. Although the first surface 41 of theflexible member can also be contoured, this is not necessary in allembodiments.

FIG. 16 illustrates a flexible member 30 having a non-uniform variationin its thickness. Thickness variations such as these are used to matchthe shape of muscle, other tissue found within the body, and the like.This feature can used to improve the placement stability of the medicaldevice within a body.

FIG. 17 illustrates a bottom view of yet another embodiment in which thesecond surface of the flexible member 44 comprises ridges 171 forstabilizing placement of the medical device 10. Ridges such as these areuseful for preventing longitudinal motion of the flexible member when incontact with the body tissue.

Referring to FIG. 18, the shape of the flexible member can be preformedto mate with a perimeter of the medical device. The flexible member 30comprises extensions 182 that are formed to mate with the surface of thehousing 32, and are positioned at points about the perimeter 47 of thehousing surface. In one embodiment, these extensions 182 form acontinuous ridge on the first surface 41 of the flexible member,encircling the perimeter 47 of housing surface 32 and facilitatingaccurate alignment with the housing 11. The first surface 41 can becoated with an adhesive to facilitate attachment to the surface of thehousing 32.

FIGS. 19 and 20 illustrate embodiments comprising a second surface 44 ofthe flexible member with different textures. These textures can include,for example, bumps or hair-like tentacles. These textures can beunidirectional (as shown in FIG. 20) or can be oriented in multipledirections. Textures can be formed as an integral part of the flexiblemember, or they can be attached to a surface of the flexible memberafter it has been formed. Although FIGS. 19 and 20 show the entiresecond surface 44 of the flexible member covered with a texture, in someembodiments only a portion of the second surface 44 is covered.Moreover, combinations of the different types of textures can be used onthe same flexible member. The first surface 41 of the flexible membercan also have a texture, although a smooth surface is generallypreferred to promote more effective adhesion with the housing surface32.

The suture locations 38 can be an important element of some embodimentsof the invention. In one embodiment, the suture locations 38 comprisepermeable portions of the perimeter region 35 of the flexible member 30,such as a permeable membrane. For example, the suture locations in eachof the embodiments described above comprising a perimeter region 35 canhave one or more suture locations 38 including a permeable membrane. Apermeable membrane is any biocompatible material that a physician canpenetrate with a suture needle, either before or during implantation ofthe medical device within the body of a patient. A perimeter region 35can comprise zero, one, or a plurality, of suture locations.Furthermore, in some embodiments the entire perimeter region 35 can bepenetrable by a suture needle, and thus can function as a large suturelocation 38. In still other embodiments, the entire flexible member 30can be penetrable by a suture needle.

For embodiments comprising a permeable membrane, the suture location 38is generally made of a material that closes back about the suture orsuture needle after the material has been penetrated. Suture locationssuch as these can be penetrated one time or multiple times by a sutureneedle. Generally, a physician penetrates a given point within a suturelocation only once with a suture needle, although the same point on asuture location can be penetrated multiple times. However, a suturelocation can readily be sutured multiple times by a physician ifmultiple sutures are to be attached to that suture location, and thesesutures can be positioned at the same or different points. The suturelocation thus comprises a permeable membrane that can be penetrated atmultiple different locations. Multiple sutures can thus be locatedadjacent to each other, can be scattered about the suture location 38,or can be scattered about the perimeter region 35, all at the discretionof the physician. This is a useful feature in that a physician does nothave to determine before surgery if, or how many, sutures are needed, orprecisely at what locations about the medical device 10 they will beplaced.

The decision to attach any sutures to the medical device at all is atthe discretion of the physician. Stabilization of the placement of themedical device 10 within a body using the flexible member 30, withoutsuturing, and either with or without the presence of suture locations,represents a preferred embodiment for some physicians.

In other embodiments, suture holes 14 may be punched into suturelocations 38. Suture locations 38 in each of the embodiments describedabove can have one or more suture holes 14. The use of suture holes 14eliminates the need for a physician to force a suture needle through thematerial of the suture location 38. More than one hole may be located ina suture location, and suture holes can be conveniently punched into theflexible member 30 before surgery using simple tools. Alternatively,suture holes 14 can be preformed at suture locations 38 about theperimeter region 35 of flexible member 30 at the time of manufacture.

In some embodiments prepunched patterns are formed, for example, in theperimeter region 35 or on the tabs 72 of the flexible member 30 tofacilitate the creation of suture holes 14. Holes prepunched in thismanner each have an easily removable plug, the removal of which createssuture holes 14 ready for use by a physician.

Although reference to sutures, suturing, and suture needles has beenmade above, the invention is equally applicable to staples, hooks, andother devices and means known to those of skill in the art for placing,securing, or attaching devices within a body. Use of the terms sutureand suturing is intended to include these other devices and methods.

Furthermore, the above discussion has centered on suture locations 38disposed within the perimeter region 35 specifically, and generallywithin the flexible member 30. However, the invention also includessuture locations 38 disposed within tabs 72, as discussed above. Thesesuture locations can include suture holes 14, or not. As with theflexible member 30 and the flexible region 35, these tabs are preferablyfoldable and flexible.

In embodiments, the suture holes 14 can be filled with a fillingmaterial. This filling material can be added to the suture hole 14before surgery, and preferably during manufacture of the flexible member30. The filling material should be formed of a soft material such assilicone that can be penetrated by a suture needle, and that will closeabout a suture after suturing. Other materials can be used to fill thesuture holes 14, such as CORETHANE® (registered mark of CorvitaCorporation, Miami, Fla.), polyurethane, and bionate polycarbonateurethanes. Materials with a Durometer reading of 50-55 are preferred forthis purpose. Such materials are relatively soft, and can beconveniently punctured with a needle. An appropriate material thicknessshould be used, as is apparent to one of ordinary skill in the art. Thesuture holes 14 can be filled or pre-filled with the filling material.The presence of the filling material in the suture hole 14 minimizestissue ingrowth into the suture hole, making subsequent removal of themedical device less difficult.

Additionally the flexible member 30, and the medical device, can becoated with a material, for example, to inhibit tissue ingrowth.Suitable coatings include but are not limited to antimicrobial coatingsfor the prevention of microbial biofilming, hydrogel coatings, zincoxide coatings for preventing surface irritation, various blockcopolymers, tackifying resins, and polybutene. The medical device andthe flexible member can also be impregnated with an antimicrobialsubstance, preferably at least in a portion of the device that will belocated near the cutaneous layer 151.

FIG. 21 is a flow chart illustrating steps that can be used tomanufacture a flexible member. First the desired shape, thickness,contours, and textures of the flexible member are determined (step 211).The locations of all the desired suture locations 38 are next determined(step 212). Which suture locations 38 will comprise tabs 72 and whichwill comprise perimeter regions 35 is next determined. Since tabs caneasily be removed later, additional tabs can be included that perhapsmight not be used during implantation of the device. A pattern can becreated for the flexible member (step 214) and a suitable polymer sheetselected (step 215). Preferably, the thickness regions 156, 157,extensions 182, surface textures, and contours of the flexible memberare achieved by selecting a polymer sheet possessing the desiredcharacteristics.

A shape corresponding to the pattern can then be cut from a polymersheet (step 216), such as silicone. Any pre-planned suture holes 14 cannext be added to the tabs 72 and the perimeter regions 35 (step 217).These can be added, for example, by puncturing. Optionally, any sutureholes 14 that have been formed in step 217 can be filled with asubstance to inhibit tissue growth into the suture hole (step 218).Finally, at the discretion of the physician, additional suture holes canbe added to suture locations 38 and any unwanted tabs 72 can be severedfrom the flexible member, at the time of surgery (step 219).

To complete the manufacture of a medical device, a housing, such as thatof an implantable port, is provided. The flexible member is thenattached to a surface of the medical device. When implanted within thebody, the medical device exhibits improved placement stability.

Other embodiments of the manufacturing process are also possible. Forexample, an adhesive coating can be applied to the flexible member afterit has been cut from the polymer sheet, or the polymer sheet cancomprise an adhesive material before the cutting is performed.Preferably, the adhesive is applied to the sheet of polymer material byat least one of slot coating, spiral spraying, melt blowing, patterncoating, layering, dipping/drying, and ion deposition.

Suitable biocompatible adhesives are known to those of ordinary skill inthe art, and include water-based adhesives, methoxy-perfluoropropane,and thixotropic sealants. Such adhesives can be coated continuously ordiscontinuously, and are compatible with muscle, tissue, skin surfaces,and the like. The first surface 41 of the flexible member comprises suchan adhesive, for contacting the housing surface 32. Optionally, the sameor a different adhesive can be applied to the second surface 44 of theflexible member, for contacting tissue layer 154. Tissue-specificadhesives can also be used. The application of adhesive to the secondsurface 44 of the flexible member contributes to the placementstabilization of the medical device 10. Adhesives of low or moderatetacking strength can also be used on either surface, to facilitaterepositioning or removal of the flexible member. Preferably, theadhesive selected for this purpose will not leave a residue or exhibitany adhesive transfer to the tissue surface 154 upon removal orrelocation of the medical device 10. Materials left behind after removalof the medical device can adversely affect healing of the body.

The flexible member 30 can be manufactured from many differentmaterials. Preferably, the flexible member is formed from at least oneof thermoplastics, elastomers, polyurethanes, and fiber reinforcedelastomers. Suitable fibers for this purpose include polyester orKevlar® fiber. Kevlar® is a registered trademark of E. I. duPont deNemours and Company. The flexible member can also be manufactured frommaterials such as a latex/plastic polymer blend, silicone, vinyl, foam,rubbers, varying percentages of rubbery block co-polymers and midblockscomprising ethylene/propylene and ethylene/butylene, and mixturesthereof, S-EP block co-polymers (styrene-ethylene/propylene),dycyclopentadiene, fully hydrogenated aliphatic C5 and C9 resins, andalpha-methylstyrene based resins.

Various packaging and usage options are within the scope of theinvention. For example, a package can be sold that includes a set ofpre-cut flexible members or “frames.” The physician can then select thedesired style from the set, attach it to the medical device, and performthe implantation. The package can include flexible members with, forexample, a one, two, or three-hole option. The physician merely selectsthe flexible member that meets his needs and preferences. Optionally, ifdesired, the medical device can be trimmed and/or suture holes can beadded, before attaching a flexible member.

FIG. 22 is a flow chart illustrating steps that can be used by aphysician to select and prepare the flexible member for use. A physicianopens a package containing a number of flexible members (step 221). Oneof the flexible members from the package is selected. The flexiblemember selected should have tabs 72 and perimeter regions 35 in at leasteach of the locations desired (step 222). Extra, unwanted tabs can beremoved by cutting (step 223). Any additional suture holes 14 can beadded (step 224), for example, by puncturing. Optionally, a fillingmaterial such as silicone can be added to any suture holes that have notbeen prefilled, to prevent or minimize tissue ingrowth. These unfilledsuture holes can be filled by the physician or his staff before surgery,or after implantation into the body of a patient (described below). Theunfilled suture holes could have been formed, for example, in citherstep 224 or step 217.

FIG. 23 is a flow chart illustrating steps that can be used to implantand secure a medical device 10 comprising a flexible member 30 into abody. Various methods can be used for this purpose. The physician firstdetermines the location and number of suture locations desired andprepares the flexible member as described in FIG. 22 (step 231). If theflexible member has tabs 72, any undesired tabs are removed. Ifinsufficient suture holes 14 are present, more can be added bypuncturing the appropriate suture location(s) of the flexible member.More than one suture hole can be added to each suture location,depending upon the physician's preference.

A linear incision is made in the patient (step 232). The incision is ofreduced size, due to the planned usage of the flexible member. Theflexible member can be adhesively attached to the housing surface 32 atthis time (step 233), or it can be attached later. Attaching it laterallows the smallest incision size to be used.

The housing 11 and the flexible member 30 are inserted through theincision, into the body of the patient, near an area in which thecatheter 22 is to be placed. The physician positions the catheter, andthen positions the flexible member adjacent the tissue layer 154 (step236). The flexible member is then sutured into place (step 237). Thiscan be done by sewing subcutaneous sutures through the suture locations38, thereby securing the flexible member 30 to adjacent tissue. Theflexible member is now attached to the housing surface 32, if it has notalready been attached (step 238). The incision is then closed andbandaged (step 239).

The sutures can thus be used to anchor the tissue layer 154 and/or thecutaneous layer 151 to the medical device 10. In other embodimentstissue can be anchored the medical device using subcutaneous hooks andother devices and methods known to the skilled artisan.

In some embodiments the flexible member 30 or the housing 11 can becoated with materials that promote tissue growth to provide bettersealing of the incision, such as collagen or other tissue growthcatalysts and substances. Materials that promote ingrowth of cells, suchas a permeable fabric, a textured polymer, or appropriate mesh materialscan also be bonded to or embedded into the surface of medical device 10.The added ingrowth materials cause the skin surrounding the medicaldevice 10 to bond securely with the medical device 10. Alternatively,growth inhibition materials can be placed on or around the medicaldevice. For example, suture holes 14 that will not be used can be filledwith silicone to prevent tissue ingrowth. Thus, fibrin will not growinto these suture locations, and the medical device can later be moreeasily removed.

The flexible member of the invention is suitable for use with variousmedical devices including implantable venous ports, PEG ports, and otherepidermal and indwelling medical devices that, for example, provideaccess to the body or to vasculature. These include devices used forgastrointestinal feeding and metering, intervascular pumps, insulinpumps, drainage products (such as for draining an abscess), pacingproducts (such as pacemakers), and various catheters.

While the invention has been particularly shown and described withreference to specific preferred embodiments, it should be understood bythose skilled in the art that various changes in form and detail may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

What is claimed:
 1. A vascular access device comprising: a housingcomprising an entry site and a housing perimeter; wherein aneedle-penetrable material is configured to extend asymmetrically fromthe housing perimeter; and wherein the needle-penetrable materialcomprises a non-uniform variation in thickness.
 2. The vascular accessdevice of claim 1, wherein the needle-penetrable material is configuredto be shaped to mate with the housing.
 3. The vascular access device ofclaim 1, wherein the needle-penetrable material is configured to extendasymmetrically from the housing perimeter in at least more than onedirection.
 4. The vascular access device of claim 1, wherein theneedle-penetrable material is devoid of any preformed suture holes andis configured to allow complete penetration by a needle.
 5. The vascularaccess device of claim 1, wherein the vascular access device isconfigured to allow for the administration, withdrawal, or exchange of afluid.
 6. The vascular access device of claim 5, wherein the vascularaccess device is configured to allow for the withdrawal of blood.
 7. Thevascular access device of claim 6, wherein the vascular access device isconfigured to allow for the administration of blood.
 8. The vascularaccess device of claim 1, wherein the needle-penetrable material isconfigured to surround a majority of the housing perimeter.
 9. Thevascular access device of claim 1, wherein the housing further comprisesa septum.
 10. The vascular access device of claim 1, wherein thenon-uniform variation in thickness of the needle-penetrable material isconfigured to extend along at least one surface of the housing.
 11. Avascular access device comprising: a housing comprising a housingperimeter; a needle-penetrable material configured to surround amajority of the housing perimeter; wherein the needle-penetrablematerial is configured to allow complete penetration by a needle toattach a suture; and wherein the needle-penetrable material isconfigured to vary in thickness along at least one surface of thehousing.
 12. The vascular access device of claim 11, further comprisinga base and an entry site; and wherein the needle-penetrable material isconfigured to extend from the entry site to the base.
 13. The vascularaccess device of claim 12, wherein the vascular access device furthercomprises a catheter.
 14. The vascular access device of claim 13,wherein the needle-penetrable region is devoid of any performed sutureholes.
 15. A vascular access device comprising: a housing comprising anentry site and a base; wherein a needle-penetrable material is devoid ofany preformed suture holes and is configured to allow completepenetration by a needle; wherein the needle-penetrable material isconfigured to extend from the entry site to below the base; and whereinthe needle-penetrable material comprises a region of a first thicknessand a region of a second thickness.
 16. The vascular access device ofclaim 15, wherein the housing further comprises a septum.
 17. Thevascular access device of claim 15, wherein the vascular access deviceis configured to allow for the withdrawal of blood.
 18. The vascularaccess device of claim 17, wherein the vascular access device isconfigured to allow for the administration of blood.
 19. The vascularaccess device of claim 18, wherein the first thickness is greater thanthe second thickness.
 20. The vascular access device of claim 19,wherein the housing further comprises a housing perimeter; and whereinthe needle-penetrable material is configured to extend asymmetricallyfrom the housing perimeter.